EP 0887624 A3 19990210 -
Publication
Application
Priority
JP 17250497 A 19970627
Abstract (en)
[origin: EP0887624A2] An optical fiber distortion measurement system (i.e., device and method) is provided to perform measurement on a measured optical fiber, which is constructed by alternatively connecting two kinds of optical fibers whose Brillouin frequency shifts are different from each other. Herein, the system sequentially supplies optical pulses to the measured optical fiber while changing their light frequencies, so that Brillouin backscattering beams are output from the measured optical fiber. At first, the system supplies an optical pulse having a prescribed light frequency to the measured optical fiber of a non-distortion state, so that the device produces initial data representing time-related variations of light intensity of Brillouin backscattering light output from the measured optical fiber. Then, the system measures a time-related variation waveform representing light intensity of Brillouin backscattering light, which is output from the measured optical fiber supplied with the optical pulse of the prescribed light frequency. By comparing the measured time-related variation waveform with the initial data, the system determines occurrence of distortion in the measured optical fiber. Thereafter, the system discriminates a kind of the distortion, which corresponds to expansion or contraction, on the basis of a relationship between Brillouin frequency shifts, which are respectively calculated with respect to a detection point and its adjacent point on the measured time-related variation waveform. Incidentally, the Brillouin frequency shift is calculated in accordance with a quadratic approximation formula, which is created on the basis of the initial data. <IMAGE>
IPC 1-7
IPC 8 full level
G01M 11/00 (2006.01); G01D 5/353 (2006.01); G01M 11/02 (2006.01)
CPC (source: EP US)
G01D 5/35303 (2013.01 - EP US)
Citation (search report)
- [A] DE 19638390 A1 19970327 - ANDO ELECTRIC [JP], et al
- [A] US 5627927 A 19970506 - UDD ERIC [US]
- [A] PATENT ABSTRACTS OF JAPAN vol. 018, no. 187 (P - 1720) 30 March 1994 (1994-03-30)
- [A] TOSHIO KURASHIMA: "BRILLOUIN OPTICAL-FIBER TIME DOMAIN REFLECTOMETRY", IEICE TRANSACTIONS ON COMMUNICATIONS, vol. E76-B, no. 4, 1 April 1993 (1993-04-01), pages 382 - 389, XP000378270
- [A] GARUS D ET AL: "BRILLOUIN OPTICAL-FIBER FREQUENCY-DOMAIN ANALYSIS FOR DISTRIBUTED TEMPERATURE AND STRAIN MEASUREMENTS", JOURNAL OF LIGHTWAVE TECHNOLOGY, vol. 15, no. 4, April 1997 (1997-04-01), pages 654 - 662, XP000691032
Designated contracting state (EPC)
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
EP 0887624 A2 19981230; EP 0887624 A3 19990210; JP 3085246 B2 20000904; JP H1123415 A 19990129; US 5949533 A 19990907
DOCDB simple family (application)
EP 98111574 A 19980624; JP 17250497 A 19970627; US 10231698 A 19980622